It is highly desirable that a clutch have snap action in the clutching and declutching operation thereof, in order to reduce clutch slippage and to decrease clutch lining wear. The fluid control valve of this invention is particularly adapted for controlling flow of air to an air operated clutch, but is also applicable to other types of apparatus. When the thermally responsive fluid control valve of this invention is employed with a fluid operable clutch, the clutch operates a fan in an internal combustion engine cooling system. The fan forces air through a radiator or heat exchanger which is a part of the cooling system for the internal combustion engine. The valve is operated by a thermally responsive actuator which senses the temperature of a liquid flowing through the internal combustion engine for the cooling thereof.
It is necessary to employ a thermally responsive actuator which is capable of performing a significant amount of work required for operation of the valve. Such a thermally responsive actuator is ordinarily one which employs a thermally responsive expansible material for creating relative movement between a container of the material and an actuator rod. Such a thermally responsive actuator is, by nature, relatively slow in operation. Therefore, conventional thermally responsive fluid control valves which control fluid flow to a fluid operable clutch have caused the fluid operable clutch to operate slowly. As stated above, slow operation in clutching and declutching is objectionable.
It is an object of this invention to provide a fluid control valve device which includes a thermally responsive actuator and in which the fluid control valve has snap action, for operation of any one of numerous types of mechanisms, such as a fluid operable clutch.
Another object of this invention is to provide such a thermally responsive fluid control valve device which may be constructed for fluid flow therethrough in response to elevated temperatures and which may be constructed for prevention of fluid flow therethrough in response to elevated temperatures.
It is another object of this invention to provide such a thermally responsive fluid control valve device which can be used in any one of numerous types of applications, other than in the areas of internal combustion engines and automotive situations.
Other objects and advantages of this invention reside in the construction of parts thereof, the combination thereof, the method of manufacture, and the mode of operation, as will become more apparent from the following description.